Depression and anxiety are prevalent in primary care practice, associated with substantial reductions in health-related quality of life (HRQoL), and generate a significant excess of morbidity. In response, dozens of trials have demonstrated the greater effectiveness of Collaborative Care for these conditions vs. primary care physicians' usual care. Yet for a variety of reasons, these models have not been widely implemented. Therefore, an urgent need remains to develop and test more scalable, powerful, and innovative versions of Collaborative Care while simultaneously developing a greater understanding of how best to provide these interventions through primary care where the majority of depressed and anxious patients seek treatment. Thousands of web sites provide medical information and the number of Internet support groups (ISG) where the public can exchange information about treatments is proliferating. Still, clinical trials have not established the benefits of utilizing he Internet in this manner. Concurrent with these developments, several computerized cognitive behavioral therapy (CCBT) programs have been proven effective at treating patients with mood and anxiety disorders and used by hundreds of thousands of patients outside the U.S. Yet CCBT remains little utilized inside the U.S., and no trials have incorporated CCBT into a Collaborative Care intervention or examined the effectiveness of combining CCBT with an ISG for these disorders. We propose a 4-year comparative effectiveness trial that will randomize 700 primary care patients aged 18-75 who have at least a moderate level of mood and/or anxiety symptoms and reliable access to both the Internet and e-mail to either: (1) guided patient access to Beating the Blues, a proven-effective on-line CCBT program (CCBT-alone; N=300); (2) guided patient access to Beating the Blues plus access to a moderated ISG (CCBT+ISG; N=300); or (3) their PCP's usual care (N=100). Our primary hypothesis is that patients in our CCBT+ISG arm will report a clinically meaningful 0.30 effect size (ES) or greater improvement in HRQoL on the SF-12 MCS compared to patients in our CCBT-alone arm at 6-months follow-up, and we will monitor patients for an additional 6 months to evaluate the durability of our interventions. Our secondary hypothesis is that CCBT-alone patients will report a 0.50 ES or greater improvement in HRQoL on the SF-12 MCS versus usual care at 6-months follow-up. To better understand how online mental health treatments are best provided through primary care, we will also evaluate: (a) their effectiveness across and within age strata; (b) their cost-effectiveness; (c) how patients utilize the components of our interventions; (d) patient subgroups for whom our interventions may be particularly effective; and (e) the adoption and maintenance of our interventions by practices following the Intervention Phase of the Project. Study findings are likely to have profound implications for transforming the way mental health conditions are treated in primary care and focus further attention to the emerging field of e-mental health by other U.S. investigators. PUBLIC HEALTH RELEVANCE: Depression and anxiety are common in primary care practice and are associated with substantial reductions in health-related quality of life. This Project will test the comparative effectiveness of two on-line treatments for these conditions provided through the context of a Collaborative Care program: (1) moderated access to a proven-effective computerized cognitive behavioral therapy (CCBT) program; versus (2) moderated access to CCBT plus an Internet support group (CCBT+ISG). The Project will also compare the effectiveness of these treatments to PCPs' usual care for these conditions, and evaluate the adoption and maintenance of CCBT+ISG by practices following the conclusion of the trial to provide a greater understanding of how to best scale the delivery of these interventions into a variety of primary care settings.